Abstract
It has been demonstrated that the resistance to bile flow lies in the tenacity of the duodenum, rather than in the activity of a separate sphincter at the orifice of the common duct. 1 , 2 When the duodenum is in a normal state of tonus, the secretory pressure of the liver causes the bile to be stored in the gall bladder under pressure. Besides the intra gall bladder pressure caused by elasticity of the organ, it has been claimed that there is forceful contraction of its musculature in expulsion of bile. 3 , 4 , 5 , 6 Hendrickson 7 has shown that the smooth muscle tissue of the gall bladder of man and dog is relatively sparse, and not arranged in coats, as we might expect of an organ possessing marked powers of contraction. However, if the gall bladder possesses strong capabilities of contraction, it should, when in such a balanced physiological state as to display tonus rhythm, respond to one of the following means of excitation: activity of the duodenum; hormone action; stretching, as when distended by bile; drugs that act either directly or indirectly upon smooth muscle.
In dogs under light anesthesia with a small rubber balloon in the gall bladder connected with a water manometer, normal rhythmical tonus changes were recorded. No relationship between these and activity of the duodenum was found to exist. Pilocarpine and eserin tended to increase the tonus while adrenalin and atropine had the opposite effect. Barium chloride produced definite augmentation of the tonus rhythm. No strong contractions were produced by drug action.
A fat meal never brought about contraction in cat or dog, even when the gall bladder was distended. Following such a meal the bile pressure is increased by hepatic secretion.
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